In a surveillance camera or onboard camera, an image pickup optical system having a wide angle of view is employed to get a wide image pickup range with one camera. The image pickup optical system having a wide angle of view has been disclosed in several proposals. For example, a system having an angle of view of about 150 degrees has been proposed, as disclosed in Japanese Non-Examined Patent Publication Nos. 2003-307674 and 2005-227426.
However, the optical system described in Japanese Non-Examined Patent Publication 2003-307674 requires use of many lenses. This results in a cost increase and difficult lens assembling. Further, the optical system described in Japanese Non-Examined Patent Publication 2005-227426 is not suitable for use in a surveillance camera or onboard camera which is employed in an environment affected by great temperature fluctuation.